Chapter 6: Creating and Managing Indexes Using PROC SQL
Correct answer: d
The index that is specified
is based on one column, so it is a simple index. In the CREATE INDEX
statement, you specify the index name after the keywords CREATE INDEX.
You do not include a keyword to specify that this is a simple index.
The name of the key column is specified in parentheses after the table
name. The name of a simple index must be the same as the name of the
key column.
Correct answer: b
To create a unique index,
the UNIQUE keyword is added to the CREATE INDEX statement, between
the keywords CREATE and INDEX.
Correct answer: d
A composite index is
based on two or more columns. In the CREATE INDEX statement, you specify
the index name after the keywords CREATE INDEX. You do not include
a keyword to specify that this is a composite index. The names of
the key columns are specified in parentheses after the table name.
The name of a composite index cannot be the same as the name of any
columns in the table.
Correct answer: a
Specifying the option
MSGLEVEL=I causes informational messages about index usage to be written
to the SAS log.
Correct answer: c
The DROP INDEX statement
drops one or more specified indexes from a table. You specify the
name of each index to be dropped after the keywords DROP INDEX. The
table name is specified after the keyword FROM. The type of index
and the names of the indexed columns are not specified in the statement.
Correct answer: b
The DESCRIBE TABLE statement
lists all indexes for one or more tables that you specify, along with
other information about the table(s).
Correct answer: a
The IDXWHERE=YES data
set option tells SAS to use the best available index, even if the
index does not optimize performance.
Correct answer: c
Indexes can be created
on either character or numeric columns.
Correct answer: d
Using an index will
optimize specific classes of PROC SQL queries. A query in which the
key column is specified only in a SELECT clause is not one of these
queries.
Correct answer: c
The IDXNAME= data set
option directs PROC SQL to use an index that you specify. The specified
index must exist and must be suitable by having at least its first
or only column match the condition in the WHERE expression.